[638RS]

In comparing my fuel flow numbers to two other similar equipped planes my fuel flows are lower by 1 to 2 GPH and I am wondering if I am producing full power on TO.

I am running a 0-360 w. 9.1 pistons, one EI/mag and FP prop. On takeoff my fuel flow is reading 15.1 ?15.5 GPH @ 2450 ?2500 rpm. At 2500 ft WOT I am burning ~16 gph @ 2700 RPM. Comparable fuel flows in similar aircraft seem to be 17 to 17.5 gph, In fact my engine test sheet reads 17.6 GPH @ 2700 rpm at sea level.

My fuel flow gage is routinely accurate to .1 - .2 gal on fill up so I believe the fuel flow number is accurate. Unless it is possible for the FF gauge to be accurate in gal used over time but off in instantaneous readings.

My manifold pressure on TO is within one point of ambient so that would indicate a WOT and no induction losses.

BTW, I get close to book speed?.

 

[scsmith]

Just a little leaner than others?

The richer-running airplane is probably not making much more power, just wasting gas. I think you should verify that you are about 100F rich of peak (or more), to be safe.

On my maiden flight on 9/8/09, I was getting around 16.5 gph WOT for an IO-360 angle valve w/8.7:1 pistons. I have not tuned the fuel flow meter calibration yet, just using the calibration number that was supplied with it for starters.

I did check at 25 squared and found I am 150F rich of peak.

 

[638RS]

Thanks Steve...

I know that I am running better than 100 degrees rich of peak so I am going to quit worrying about it and enjoy the gas savings. I'll check the actual value the next time I fly...